U.S. patent application number 13/889755 was filed with the patent office on 2013-11-14 for construction vehicle for preparation of a road surface.
The applicant listed for this patent is Bomag GmbH. Invention is credited to Manfred Hammes, Jens-Martin Zehbe.
Application Number | 20130300182 13/889755 |
Document ID | / |
Family ID | 49475252 |
Filed Date | 2013-11-14 |
United States Patent
Application |
20130300182 |
Kind Code |
A1 |
Hammes; Manfred ; et
al. |
November 14, 2013 |
CONSTRUCTION VEHICLE FOR PREPARATION OF A ROAD SURFACE
Abstract
The invention relates to a construction vehicle for preparation
of a road surface, more particularly a road milling machine or a
ground stabilizer, comprising a rotatably driven milling cutter,
more particularly a milling rotor or a milling drum, and a drive
unit for a milling tool, comprising a drive motor and a gear unit
interposed between the drive motor and the milling cutter, wherein
the gear unit is in the form of a cogwheel gearbox and comprises at
least two gear pairings having different gear ratios, wherein the
gear pairings can be selectively engaged to form part of the drive
connection or disengaged therefrom.
Inventors: |
Hammes; Manfred;
(Emmelshausen, DE) ; Zehbe; Jens-Martin;
(Schoningen, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Bomag GmbH |
Boppard |
|
DE |
|
|
Family ID: |
49475252 |
Appl. No.: |
13/889755 |
Filed: |
May 8, 2013 |
Current U.S.
Class: |
299/39.4 |
Current CPC
Class: |
E01C 23/088 20130101;
E01C 23/127 20130101; E01C 2301/00 20130101 |
Class at
Publication: |
299/39.4 |
International
Class: |
E01C 23/088 20060101
E01C023/088 |
Foreign Application Data
Date |
Code |
Application Number |
May 10, 2012 |
DE |
102012009310.1 |
Claims
1. A construction vehicle for preparation of a road surface,
comprising: a rotatably driven milling cutter; and a drive unit for
a milling tool comprising a drive motor and a gear unit (12)
interposed between said drive motor and said milling cutter,
wherein said gear unit is in the form of a cogwheel gearbox and
comprises at least two gear pairings having different gear ratios,
wherein the at least two gear pairings can be optionally engaged to
form part of the drive connection or disengaged therefrom.
2. The construction vehicle according to the claim 1, wherein a
first clutch is assigned to a first of the at least two gear
pairings and a second clutch is assigned to a second of the at
least two gear pairings, wherein the act of closing one of the two
clutches causes the respectively assigned first or second gear
pairing to be engaged to form part of the drive connection or to be
disengaged therefrom.
3. The construction vehicle according to claim 1, wherein the drive
unit comprises a dual clutch transmission.
4. The construction vehicle according to claim 1, wherein said
first and second clutches respectively assigned to said first and
second gear pairings are connected in parallel and the drive
connection between said drive motor and an output shaft of said
gear unit can be interrupted exclusively via said first and second
clutches.
5. The construction vehicle according to claim 1, wherein a torsion
vibration damper is disposed between said gear unit and said
milling cutter.
6. The construction vehicle according to claim 1, wherein the
construction machine comprises a road milling machine.
7. The construction vehicle according to claim 1, wherein the
construction machine comprises a ground stabilizer.
8. The construction vehicle of claim 1, wherein the rotatably
driven milling cutter comprises a milling rotor.
9. The construction vehicle of claim 1, wherein the rotatably
driven milling cutter comprises a milling drum.
10. The construction machine of claim 5, wherein the vibration
damper comprises a belt drive.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority under 35 U.S.C.
.sctn.119 of German Patent Application No. 10 2012 009 310.1, filed
May 10, 2012, the disclosure of which is hereby incorporated herein
by reference in its entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to a construction vehicle for
preparation of a road surface, in particular, a road milling
machine.
BACKGROUND OF THE INVENTION
[0003] An example of such a construction vehicle is disclosed in DE
20 2007 010 294 U1. The latter comprises a milling drum mounted on
a vehicle frame and driven by a diesel engine. Disposed downstream
of the diesel engine is a transmission for transferring the drive
power to the milling drum and to other transmissions connected in
parallel.
[0004] A fundamental problem with such construction vehicles
relates to the extremely high degree of oscillation, vibration, or
shaking which is generated by the milling tool and is referred to
below in general as "vibration". This vibration can spread to
substantially the entire construction vehicle unless damping
measures are taken. Thus, individual measures aimed at decoupling
individual vehicle components from the milling tool are always
taken. For example, DE 10 2007 028 812 A1 concerns the decoupling
of the driver's cab from the vibration generated by the milling
tool.
[0005] The vibration produces a considerable amount of stress on
the vehicle components. In order to ensure the durability of the
drive motor, hitherto an attempt has always been made to decouple
the drive motor as far as possible from the milling tool in terms
of vibration. A currently widespread option is the use of a pump
transfer gear, as described in the aforementioned document DE 20
2007 010 294 U1. The transmission of drive power between the drive
motor and the milling tool is then achieved, at least partially,
exclusively via the hydraulic pressure of a hydraulic fluid. The
known damping properties of such a hydraulic fluid are then
sufficient for adequately damping critical vibration.
[0006] The use of pump transfer gears is still widespread. This may
be due to the fact that with such a pump transfer gear, a power
take-off is easily engaged by operatively connecting other
hydraulic motors. The disadvantages of such pump transfer gears,
however, reside in the fact that their efficiency is somewhat poor
as well as in the fact that fluid is lost resulting from leakages
inherent to such a transfer gear. The leakages furthermore prevent
precise speed synchronization between individual drives. Moreover,
a pump transfer gear is expensive to purchase and maintain. Only
pump transfer gears having a rigid gear ratio are acceptable in
terms of purchasing and maintenance costs.
SUMMARY OF THE INVENTION
[0007] Thus the object of the present invention is to provide an
improved construction vehicle of the aforementioned type and thus
to reduce costs in terms of the drive connection and/or to reduce
the aforementioned disadvantages of the prior solutions as far as
possible.
[0008] One aspect of the present invention lies, in particular, in
the use of a standard cogwheel gearbox by means of which the gear
ratio between input and output can be varied. Furthermore, such a
cogwheel gearbox readily permits the operative connection of
auxiliary units. Especially when use is made of vibration damping
means in the drive train, e.g., a belt drive interposed between the
transmission and the milling tool, it is no longer absolutely
necessary to use a pump transfer gear in order to ensure vibration
decoupling between the milling tool and the drive motor. Such a
cogwheel gearbox can be purchased and maintained at considerably
lower expense than a pump transfer gear. In addition, the use of a
cogwheel gearbox offers the advantages now described below.
[0009] Depending upon the gear selected, satisfactory to good speed
variability of the milling drum along with very high efficiency of
the completely mechanical drive are achieved. The possibility of
operating the drive motor with optimized efficiency is, at
comparably low purchasing and maintenance costs, to a large extent
independent of the speed of the milling tool required for the
operation. Compared with a fully variable drive, the cogwheel
gearbox is considerably more economical to produce. The entirely
discrete gear stages are admittedly valid arguments against the use
of a cogwheel gearbox. Compared with earlier models, however, the
improved milling tools available today permit operation within a
certain speed range, such that this disadvantage no longer
precludes the use of a cogwheel gearbox. Furthermore, the cogwheel
gearbox also offers the possibility of readily engaging and/or
disengaging power take-offs.
[0010] The speed of the milling tool can be varied quickly and
conveniently, more particularly during operation and especially
under load. To this end, the cogwheel gearbox may be provided with
different gear stages between an input shaft and an output shaft,
which can be selectively used for power transmission. A clutch
associated with the respective gear can be used for engaging or
disengaging a gear stage (gear pairing).
[0011] In one embodiment, a first clutch is associated with the
first gear pairing and a second clutch is associated with the
second gear pairing, wherein by engaging one of the two clutches,
the respective associated gear pairing can be selectively engaged
to form part of the drive connection or disengaged therefrom. In
this case, for example, two gears of a gear pairing are always in
mesh with each other. The effective engagement of this gear pairing
in the drive train is then achieved by actuating the corresponding
clutch, analogous to a dual clutch transmission as used in the
automobile industry. The advantage of this resides in the fact that
changing the gear ratio is possible without interrupting the drive
power. This aspect of using a dual clutch transmission can of
course also be applied in case of more than two gears, which is
thus comprised by the present invention. The essential advantage of
the present invention resides in the fact that this dual clutch
transmission can be engaged and disengaged without interrupting the
tractive power and therefore allows for particularly harmonic
engagement and disengagement procedures. The basic principle of the
dual clutch transmission can thus be summed up to the drive train
having two sub-transmissions with two clutches which alternately
provide for force transmission. If one clutch engages during
working operation, the other clutch will open and vice versa.
[0012] The clutches associated with the respective gear pairings
are preferably connected in parallel to each other. As intended,
the drive connection between the drive motor and the output shaft
of the transmission unit is then interrupted exclusively via these
clutches. The advantage of such an arrangement is that the clutches
required for engagement are essentially the same as those by means
of which the drive connection can be fully interrupted. There is
then no need for a separate "pre-clutch" between the drive motor
and the transmission unit.
[0013] Alternatively, a gear stage can also be engaged by bringing
the two gears of the respective gear stage into mesh with each
other. However, this requires a brief interruption of the drive
power, for instance via a clutch disposed upstream of the entire
transmission. Changing the gear ratio, however, does involve an
interruption of the drive power.
[0014] By selecting the right gear ratios, it is possible to ensure
a nearly, or at least sufficiently, steady operation of the drive
motor, thus operating the latter as far as possible in its optimum
efficiency range.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The present invention will be explained in more detail in an
exemplary and non-restrictive manner, with reference to the
figures, in which:
[0016] FIG. 1 is a diagram of a ground milling machine in its
entirety;
[0017] FIG. 2 is a diagram of a milling rotor driving mechanism
comprising a main drive and a power take-off in neutral;
[0018] FIG. 3 is a diagram of the milling rotor driving mechanism
as shown in FIG. 2 with the main drive in neutral and the power
take-off engaged;
[0019] FIG. 4 is a diagram of the milling rotor driving mechanism
as shown in FIG. 2 with the main drive engaged and the power
take-off engaged in a first gear stage; and
[0020] FIG. 5 is a diagram of the milling rotor driving mechanism
as shown in FIG. 2 with the main drive engaged and the power
take-off engaged in a second gear stage.
DETAILED DESCRIPTION OF THE INVENTION
[0021] FIG. 1 is a side view of a ground milling machine 1 (more
specifically a front-end loader type road milling machine with a
central rotor). The machine direction (forward direction) is
indicated by the arrow "a". Essential elements of the ground
milling machine include a milling device mounted in a drum housing
2, a vehicle frame 3 with a driver's station 4 and caterpillar
tracks 5 mounted in a vertically adjustable manner on the vehicle
frame 3 by means of lifting columns (alternatively, use can also be
made of wheel driving units). The ground milling machine 1 further
comprises a driving mechanism for a milling rotor, which will be
explained in more detail below. The milling rotor driving mechanism
is equipped with an internal combustion engine not indicated in any
greater detail, by means of which the necessary mechanical working
energy for operation is supplied. In the working mode, the ground
milling machine 1 is driven over the road surface 6 in the machine
direction "a" and grinds up road surface material with a milling
rotor (not illustrated in FIG. 1) disposed within the drum housing
2.
[0022] FIGS. 2 to 5 illustrate the milling rotor driving mechanism
diagrammatically. A diesel engine serves as a drive motor 11, the
output shaft 16 of which is connected to an input shaft 17 of a
cogwheel gearbox 12 for joint rotation therewith.
[0023] The drive torque is transferred via a pre-stage 20 to a
first and second intermediate shaft 21a, 21b, in each case at the
same gear ratio. A first multi-plate clutch 22a connects to the
first intermediate shaft 21a; a second multi-plate clutch 22b
connects to the second intermediate shaft 21b. The multi-plate
clutches 22a, 22b are each used for engaging a first or a second
gear stage 23a, 23b respectively. The two gear stages 23a, 23b each
comprise an input pinion gear 24a, 24b, which are connected on the
output side to the associated multi-plate clutch 22a, 22b. The two
input pinion gears 24a, 24b mesh with output pinion gears 25a, 25b.
The two gear stages 23a, 23b thus have different gear ratios. The
two output pinion gears 25a, 25b are each fix-connected to an
output shaft 26 of the cogwheel gearbox 12. The output shaft 26 in
turn drives a belt drive 14, which finally drives the milling drum
15.
[0024] Furthermore, an auxiliary unit 28, for example, a generator
or a hydraulic pump, is driven by the input shaft 17. To this end,
the input shaft drives a pinion gear 27, which continuously meshes
with another pinion gear 29, thereby continuously driving an
auxiliary shaft 30. A cut-in clutch 31 for engaging the auxiliary
unit 28 connects to this auxiliary shaft 30.
[0025] In the state illustrated in FIG. 2, the input shaft 17, the
two intermediate shafts 21a, 21b, and the auxiliary shaft 30 are
being driven. The input pinion gears 23a, 23b of the gear stages,
however, are not being driven at this moment, since the multi-plate
clutches 22a and 22b are disengaged. In order to drive the milling
drum 15, one, and only one, of the gear stages 23a, 23b must be
engaged in the drive train. To this end, only one of the two
multi-plate clutches 22a, 22b is engaged. It can be seen that the
gear ratio between the input shaft 17 and the output shaft 26b is
established by selecting one of the multi-plate clutch elements
22a, 22b for engagement.
[0026] Unlike FIG. 2, FIG. 3 shows that the cut-in clutch 30 is now
engaged. In this state, the milling drum 15 is not being driven,
whereas the auxiliary unit 28 is.
[0027] Unlike FIG. 3, FIG. 4 shows that the first multi-plate
clutch 22a is now engaged, thereby establishing a drive connection
between the diesel engine 11 and the milling drum 15. The first
gear pairing of the input pinion gear 24a and the output pinion
gear 25a of the first gear stage 23a are now part of the drive
connection.
[0028] Unlike FIG. 4, FIG. 5 shows that the second multi-plate
clutch 22b rather than the first multi-plate clutch 22a is engaged.
Thus the drive connection between the diesel engine 11 and the
milling drum 15 is still established, but with a different gear
ratio. The second gear pairing of the input pinion gear 24b and the
output pinion gear 25b of the second gear stage 23b are now part of
the drive connection.
[0029] The drive connection between the output shaft 16 of the
drive motor 11 and the output shaft 26 of the transmission 12 can
be interrupted or established via the selectively engagable
clutches 22. A shifting clutch between the drive motor 11 and the
transmission 12, which is represented in the figures by dotted
lines outside the transmission housing 19 and is designated by the
reference numeral 18, is therefore unnecessary. Furthermore, this
enables variation of the gear ratio without interrupting the
traction force, so that an optimized gear ratio is provided
depending on the application. Moreover, the number of gear pairings
can be extended beyond the pairings indicated in the figures, so
that the differences between the gear stages can be reduced,
enabling optimized operation of the drive over a broad range of
different rotational speeds of the milling drum.
[0030] Ideally, the multi-plate clutches 22a, 22b are connected
functionally, for example, in such a manner that the clutches are
prevented from both engaging simultaneously. Accordingly, the
connection occurs in such a manner that only clutch 22a, or only
clutch 22b respectively, is engaged while the respective other
clutch is disengaged. This is achieved, in particular, by the
configuration of dual clutch transmission 12a.
[0031] While the present invention has been illustrated by
description of various embodiments and while those embodiments have
been described in considerable detail, it is not the intention of
Applicant to restrict or in any way limit the scope of the appended
claims to such details. Additional advantages and modifications
will readily appear to those skilled in the art. The invention in
its broader aspects is therefore not limited to the specific
details and illustrative examples shown and described. Accordingly,
departures may be made from such details without departing from the
spirit or scope of Applicants' invention.
* * * * *